Heat exchanger comprising a liquid-refrigerant distribution device

ABSTRACT

This heat exchanger can include parallel plates which define liquid-refrigerant passages following a longitudinal direction, and—fins extending in each passage in a lateral direction orthogonal to the longitudinal direction, each fin having orifices for the flow of the liquid refrigerant. At least one lower portion of at least one fin defines, with the plate secured to this lower portion, a distribution channel for channeling the liquid refrigerant in the lateral direction. The orifices in said at least one fin are formed by overflow openings in the upper portion. The liquid refrigerant flows through the overflow openings when the or each distribution channel is full of liquid refrigerant.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a § 371 of International PCT ApplicationPCT/EP2016/052524, filed Feb. 5, 2016, which claims the benefit ofFR1550960, filed Feb. 6, 2015, both of which are herein incorporated byreference in their entireties.

TECHNICAL FIELD OF THE INVENTION

The present invention concerns a heat exchanger comprising adistribution device configured for distributing a liquid refrigerant ina heat exchanger. The heat exchanger may in particular be a vaporizerused in a column for air separation by cryogenic distillation to ensurevaporization of a liquid in the column vessel, for example liquidoxygen, by the exchange of heat with a calorigenic gas, for example airor nitrogen.

The present invention is used in particular in the field of cryogenicgas separation, in particular of cryogenic air separation (known underthe acronym “ASU” for air separation unit), which is used for productionof pressurized gaseous oxygen. In particular, the present invention maybe applied to a heat exchanger which vaporizes a liquid flow, forexample oxygen, nitrogen and/or argon, by exchange of heat with a gas.

BACKGROUND OF THE INVENTION

If the heat exchanger is located in the vessel of a distillation column,it may constitute a vaporizer functioning as a thermosiphon for whichthe exchanger is immersed in a bath of liquid descending the column, ora vaporizer functioning by film vaporization supplied directly by theliquid falling in the column, and/or by a recirculation pump.

The technology currently used for these phase change exchangers is thatof aluminum exchangers with brazed plates and fins, which leads tohighly compact devices offering a large exchange area. These exchangerscomprise plates between which fins are inserted, thus forming a stack ofvaporization passages and condensation passages, the first beingintended for vaporizing the liquid refrigerant and the second forcondensing a calorigenic gas.

WO-A-2011110782 describes a distribution device comprising parallelplates which define passages for the liquid refrigerant, and severalfins which extend in each passage and have orifices for distributing theliquid refrigerant in the lateral direction.

However, in a distribution device of the prior art, the distribution ofthe liquid refrigerant in the lateral direction is not perfectlyuniform. When zones of the exchanger do not receive sufficient liquidrefrigerant, solid deposits of impurities may occur due to dryvaporization. Such solid deposits of impurities create a risk ofexplosion in certain operating conditions of the heat exchanger.

A solution known from document EP-A-0130122 consists of piercingorifices in the parallel plates of the distribution device in order toensure a rough pre-distribution of the liquid refrigerant along thepassages for said liquid. However, the number of orifices arranged alongthe exchanger is limited in order not to complicate production or weakenthe structure, and the effect of standardizing the distribution of theliquid remains insufficient.

SUMMARY OF THE INVENTION

The object of certain embodiments of the present invention is inparticular to solve the above-mentioned problems in full or in part byproviding a distribution device in which the distribution of the liquidrefrigerant is as uniform as possible.

To this end, the object of certain embodiments of the invention is aheat exchanger configured for transferring heat from at least onecalorigenic fluid, for example nitrogen, to at least one frigorigenicfluid, for example oxygen, the heat exchanger comprising at least platesarranged parallel to each other so as to define a first series ofpassages configured for conducting liquid refrigerant globally in alongitudinal direction extending in the vertical direction duringoperation, each passage being defined between two successive plates, anda second series of passages configured for conducting a calorigenicfluid globally in the longitudinal direction, each passage being definedbetween two successive plates, the passages of the second series beinginterposed between two passages of the first series, at least one inletfor liquid refrigerant configured to pour the liquid refrigerant onlyinto the passages of the first series, and distribution means situatedin the upper end of the exchanger in passages of the first series only,comprising

fins extending in one or each passage of the first series globally in alateral direction which is orthogonal to the longitudinal direction andparallel to the plates, each passage of the first series housing severalfins succeeding each other in the longitudinal direction, each finhaving orifices configured to allow the flow of liquid refrigerant;

at least one fin having an upper portion and a lower portion, the heightof the upper portion being greater than the height of the lower portionwhen the distribution device is in operation and the longitudinaldirection extends in the vertical direction,

said at least one lower portion and the plate secured to said at leastone lower portion defining at least one distribution channel configuredfor conducting liquid refrigerant in the lateral direction,

the orifices of said at least one fin being formed by overflow openingssituated in said at least one upper portion, the overflow openings beingconfigured such that the liquid refrigerant flows via the overflowopenings when said at least one distribution channel is full of liquidrefrigerant.

In other words, the or each distribution channel forms a type of troughwhich extends between the overflow openings and an intersection of thelower portion and the plate secured to this lower portion. The or eachdistribution channel is globally horizontal when the distribution deviceis in operation.

Thus the cooperation of the or each distribution channel with theoverflow openings of the fin(s) allows distribution of the liquidrefrigerant as uniformly as possible in the lateral direction, whichlimits or prevents the risk of solid deposits of impurities in the heatexchanger.

The plates extend in two dimensions, length and width, respectively inthe longitudinal direction and the lateral direction. In each passage,the fins have longilineal forms and extend in the width (lateraldirection) of two successive plates.

The longitudinal direction is vertical when the distribution device isin operation. The liquid refrigerant flows globally in the longitudinaldirection under gravity. Therefore the liquid refrigerant flows globallyvertically in the descending direction.

According to a variant of the invention, the distribution device maycomprise a number of plates greater than 20, or even greater than 100.The plates thus form a stack of plates between which passages aredefined for the liquid refrigerant, in some cases alternating withconduits for the calorigenic fluid. The distribution device may have anumber of liquid refrigerant passages greater than 10, or even greaterthan 50.

In operation, the liquid refrigerant passes through the distributiondevice. The distribution device has i) an upstream portion configuredfor the inlet of the liquid refrigerant, and ii) a downstream portionconfigured for the outlet of the liquid refrigerant. The fins extendbetween this upstream portion and the downstream portion.

According to a variant of the invention, each passage has a flat,parallelepipedic form. Since each passage has a flat shape, the distancebetween two successive plates is small in comparison with the length andwidth of each successive plate. Preferably, all or some of the finsextend from one plate to the following plate. In other words, these finsare in contact with both plates. This construction allows the fins to bebrazed onto both plates, which increases the mechanical strength of thedistribution device.

In the present application, the term “in the direction of” means that adirection is substantially parallel or substantially colinear to anotherdirection or plane.

According to one embodiment of the invention, the volume of a respectivedistribution channel is less than 15%, preferably less than 10%, of thetotal volume delimited by:

-   -   i) a fin with overflow openings,    -   ii) the plate secured to the lower portion of said fin with        overflow openings, and    -   iii) the fin situated immediately upstream of said fin with        overflow openings.

Thus, because of a volume of the distribution channel, the fins withoverflow openings cannot cause too great a load loss. A low load lossavoids reducing the flow of liquid refrigerant through the fins withoverflow openings, which allows optimum regulation of this flow. Thefins with overflow openings therefore fulfil a function of distributingthe liquid refrigerant, generating only a low load loss. Eachdistribution channel is defined by at least one lower portion and by theplate secured to said at least one lower portion.

According to an embodiment of the invention, the overflow openings aredistributed over a fin uniformly in the lateral direction.

Thus, uniformly distributed overflow openings allow maximum uniformityof distribution of the liquid refrigerant. Alternatively, certainoverflow openings may be distributed non-uniformly in the lateraldirection.

According to one embodiment of the invention, an opening ratio having:

-   -   as numerator, the total area of the overflow openings situated        in a fin with overflow openings, and    -   as denominator, the total area of a face of said fin with        overflow openings,

is between 10% and 50%, preferably between 20% and 40%.

Thus, such an opening ratio contributes to minimizing the load lossgenerated by the fins with overflow openings, while ensuring an adequateflow in the distribution device.

According to one embodiment of the invention, each overflow opening hasan area between 1.5 mm² and 10.0 mm², preferably between 2.0 mm² and 5.0mm².

Thus such an area avoids totally flooding each overflow opening, whichcontributes to not reducing the flow of liquid refrigerant through eachfin.

According to a variant of the invention, some overflow openings have theform of an ellipse, for example circular. Thus such a shape offers anoverflow opening width which increases progressively, which limits theheight of the liquid refrigerant when the flow of liquid refrigerantincreases.

According to a variant of the invention, some overflow openings have theform of triangle pointing towards said at least one lower portion. Thussuch a shape offers an overflow opening width which increasesprogressively, which limits the height of the liquid refrigerant whenthe flow of liquid refrigerant increases.

According to one embodiment of the invention, an interval measured inthe lateral direction between two successive overflow openings isbetween 1 mm and 6 mm.

Thus, such an interval helps ensure a uniform distribution of liquidrefrigerant in the lateral direction while minimizing the load losscreated by the fins with overflow openings.

According to a variant of the invention, said interval is constant forthe overflow openings of at least one fin.

Thus such an interval contributes to maximizing the uniformity ofdistribution of the liquid refrigerant in the lateral direction.

In one embodiment of the invention, a minimal distance between i) anoverflow opening, and ii) the plate secured to said at least one lowerportion, lies between 1 mm and 4 mm, the minimal distance beingpreferably the same for the majority or totality of overflow openings ofa respective fin.

Thus, such a minimal distance allows a distribution channel to have arelatively large volume, which allows limitation of the number of finswith overflow openings in the distribution device.

According to one embodiment of the invention, several fins haverespective upper portions with overflow openings.

In other words, there are several stages of distribution of the liquidrefrigerant, which helps maximize the uniformity of this distribution.

According to one embodiment of the invention, the overflow openingspresent in a fin are positioned offset in the lateral direction relativeto the overflow openings present in the adjacent fin.

Thus such an offset between overflow openings contributes to increasingthe uniformity of the distribution of the liquid refrigerant in thelateral direction.

According to one embodiment of the invention, said offset between theoverflow openings present in two adjacent fins represents between 40%and 60% of the length of said interval.

In other words, the overflow openings of two successive fins in thelongitudinal direction are arranged substantially offset to each other.

Thus, such a value of the offset between overflow openings helpsmaximize the uniformity of distribution of the liquid refrigerant in thelateral direction.

According to one embodiment of the invention, at least one fin has aflat shape and extends up to said two successive plates and obliquely toeach of said two successive plates so as to form, in cross-section in aplane perpendicular to the plates and to the lateral direction, an acuteoblique angle, the oblique angle preferably being between 30° and 60°,further preferably between 40° and 50°.

Thus such a flat, oblique fin takes up relatively little space and iseasy to attach to the plates.

According to one embodiment of the invention, each fin has, parallel tothe longitudinal direction, a length between 4 mm and 10 mm, and eachfin has, parallel to the lateral direction, a width between 4 mm and 10mm, each fin being able for example to have equal length and width.

Thus, such a length and width allow a large number of fins to beincorporated in the distribution device, which increases the uniformityof distribution of the liquid refrigerant.

According to a variant of the invention, each fin has a fixing portionwhich is fixed to a plate, for example by brazing.

Thus such a fixing portion allows each fin to be attached to the platesin a simple fashion.

According to a variant of the invention, one and preferably eachoverflow opening is defined by a through orifice. Alternatively, atleast one overflow opening may be defined by a notch extending up to anedge of the corresponding fin.

According to one embodiment of the invention, the distribution devicecomprises at least one fin having orifices and placed upstream of thefin(s) with overflow openings, the orifices being distributed in thelateral direction, the number of overflow openings per fin being greaterthan 3 times, preferably than 5 times the number of orifices per fin.

Thus, the fins with orifices may fulfil a function of controlling theflow of liquid refrigerant entering the distribution device bygenerating a high load loss, while the fins with overflow openingsrather fulfil a distribution function while generating only a low loadloss. This limits the number of components to be mounted in thedistribution device since, because of the fins with orifices, there isno need to provide a perforated bar such as that in WO-A-2011110782 inorder to generate a high load loss.

According to a variant of the invention, at least two fins haveorifices, the number of orifices per fin increasing in the directionfrom upstream to downstream.

Thus, these fins with orifices allow optimum control of the flow ofliquid refrigerant entering the distribution device.

According to a variant of the invention, the interval between twosuccessive orifices, measured in the lateral direction of the fin withorifices which is situated furthest upstream, lies between 40 mm and 60mm, and the interval between two successive orifices, measured in thelateral direction of the fin with orifices which is situated furthestdownstream, lies between 6 mm and 20 mm.

Therefore, the fin with orifices which is situated furthest upstream hasthe fewest orifices, while the fin with orifices which is situatedfurthest downstream has the most orifices, the fins with overflowopenings being situated downstream of the fin with orifices which issituated furthest downstream.

Thus, the load loss generated by the fins with orifices diminishes fromupstream to downstream, while the uniformity of distribution of theliquid refrigerant increases.

According to a variant of the invention, at least one fin may have, inaddition to the overflow openings, at least one purge hole arranged atthe bottom of the lower portion. The distribution channel is then formedfrom several portions separated in twos by a purge hole through whichthe liquid refrigerant may flow. Such a purge hole allows evacuation ofthe distribution channel. Advantageously, the area of the or each purgehole is smaller than the area of an overflow opening. Thus the flowthrough the purge hole has a relatively low flow rate, which avoidsdisrupting the flow through each overflow opening close to the purgehole.

According to a variant of the invention, the total area of the openingsor of the overflow openings for a given fin increases in thelongitudinal direction, preferably by increasing the number and/or areaof the openings.

In this way, the further the liquid descends in the distribution means,the smaller the spacing between the openings. At the start, if theliquid is poorly distributed, it is forced to circulate laterally up toadjacent openings of the same fin. The greater the distance between twoopenings, the more effective the redistribution over the width.

Secondly, the object of certain embodiments of the present invention isa distribution method for distributing a liquid refrigerant in a heatexchanger, the distribution method comprising the steps:

-   -   implementing a distribution device according to the invention,    -   conducting liquid refrigerant into each passage and globally in        a longitudinal direction,    -   allowing the flow of liquid refrigerant via the orifices of fins        having orifices,    -   filling each distribution channel such that liquid refrigerant        flows via the overflow openings.

Certain embodiments of the present invention also concerns a heatexchanger configured to transfer heat from at least one from acalorigenic fluid, for example nitrous oxide, to at least onefrigorigenic fluid, for example oxygen, the heat exchanger comprising atleast one heat exchange unit, at least one liquid refrigerant inlet, theheat exchanger being characterized in that it comprises a distributiondevice according to any of the preceding claims, the distribution devicebeing arranged to supply liquid refrigerant to the heat exchange unit.

Thus such a heat exchanger limits or avoids the risk of solid depositsof impurities in the heat exchanger, and hence the risk of explosion incertain operating conditions.

The embodiments and variants mentioned above may be taken in isolationor in any technically feasible combination.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be clearly understood and its advantages willarise from the description which follows, given merely as anon-limitative example, and with reference to the attached drawings inwhich:

FIG. 1 is a diagrammatic cross-section view, in a plane perpendicular tothe lateral direction, of a part of a distribution device according to afirst embodiment of the invention;

FIG. 2 is a diagrammatic cross-section view, in plane II in FIG. 1 whichis parallel to the longitudinal and lateral directions, of the part ofthe distribution device in FIG. 1,

FIG. 3 is a diagrammatic cross-section view, in a plane perpendicular tothe lateral direction, of a part of a heat exchanger comprising thedistribution device according to the first embodiment of the invention;

FIG. 4 is a view similar to FIG. 1, illustrating the function of thedistribution device of FIG. 3;

FIG. 5 is a view similar to FIG. 2, illustrating the function of thedistribution device of FIG. 3;

FIGS. 6 and 7 are views similar to FIGS. 1 and 2 respectively,illustrating a part of a distribution device according to a secondembodiment of the invention;

FIGS. 8 and 9 are views similar to FIGS. 1 and 2 respectively,illustrating a part of a distribution device according to a thirdembodiment of the invention;

FIG. 10 is a view similar to FIG. 1, illustrating a part of adistribution device according to a fourth embodiment of the invention;

FIG. 11 is a view similar to FIG. 10, illustrating a part of adistribution device according to a fifth embodiment of the invention;

FIG. 12 is a view similar to FIG. 10, illustrating a part of adistribution device according to a sixth embodiment of the invention;

FIG. 13 is a view similar to FIG. 1, illustrating a part of adistribution device according to a seventh embodiment of the invention;

FIG. 14 is a view similar to FIG. 1, illustrating a part of adistribution device according to an eighth embodiment of the invention;and

FIG. 15 illustrates a distribution method according to the invention.

DETAILED DESCRIPTION

FIGS. 1, 2 and 3 illustrate a distribution device 1 which is configuredfor distributing a liquid refrigerant F1, in this case liquid oxygen,into a heat exchanger 2. The heat exchanger 2 is configured fortransferring heat from a calorigenic fluid F2, here gaseous nitrogen, tothe frigorigenic fluid, here oxygen. Before the transfer of heat, theliquid refrigerant F1 (FIG. 3) is in a holding tank 3 belonging to theheat exchanger 2.

The distribution device 1 comprises plates 11, 12, 13, 14 and equivalentwhich are arranged parallel to each other. The distribution device 1comprises a number of stacked plates equal to approximately 200. Each ofthe plates 11, 12, 13, 14 extends in two dimensions, respectively lengthand width, which are defined in a longitudinal direction X and a lateraldirection Y respectively.

The lateral direction Y is orthogonal to the longitudinal direction Xand parallel to the plates 11, 12, 13, 14. The longitudinal direction Xis vertical when the distribution device 1 is in operation. The liquidrefrigerant F1 globally flows in the longitudinal direction X undergravity. Therefore the liquid refrigerant F1 globally flows verticallyin the descending direction.

The plates 11, 12, 13, 14 are arranged so as to define passages 20, 30and equivalent which are configured for conducting the liquidrefrigerant F1 globally in the longitudinal direction X. Each passage 20or 30 is defined between two successive plates 11, 12, 13, 14. Eachpassage 20, 30 has a flat parallelepipedic form. The distance betweentwo successive plates 11 and 12 is small in comparison with the length(in direction X) and width (in direction Y) of each successive plate 11or 12. In the heat exchanger 2, passages 20, 30 for liquid refrigerantF1 alternate with passages of flat parallelepipedic form (not shown) forthe calorigenic fluid.

The distribution device 1 also comprises fins 21, 22, 23, 24 and 31, 32,33, 34, which extend respectively in each passage 20 and 30, globally inthe lateral direction Y. The fins 21, 22, 23, 24 extend in the passage20, while the fins 31, 32, 33, 34 extend in the passage 30. In eachpassage 20 or 30, the fins 21, 22, 23, 24, 31, 32, 33 and 34 havelongilineal forms and extend in the lateral direction Y of twosuccessive plates 11 and 12 or 13 and 14.

Each fin 21, 22, 23, 24, 31, 32, 33 or 34 has a flat shape and extendsup to two successive plates 11 and 12 or 13 and 14. Each fin 21 orequivalent extends obliquely to each of the two successive plates 11 and12 or 13 and 14 so as to form, in cross-section in a plane perpendicularto the plates and to the lateral direction Y (here the plane of FIG. 1),an oblique angle A21 which is acute. The oblique angle A21 is here 45°.

Each fin 21 or equivalent has, parallel to the longitudinal direction X,a length X21 which is here equal to 5 mm. Each fin 21 or equivalent has,parallel to the lateral direction Y, a width Y21 which is here equal to5 mm and hence equal to the length X21. Each fin 21 or equivalent herehas a fixing portion 21.5 which is flat and which is fixed by brazing toa respective plate 11 or equivalent. All fins 21, 22, 23, 24 extend fromone plate 11 up to the next plate 12. In other words, these fins 21, 22,23, 24 are in contact with both plates 11 and 12. The fins 21, 22, 23,24 are brazed onto the two plates 11 and 12.

Each passage 20 or 30 here houses four fins, respectively 21, 22, 23, 24and 31, 32, 33, 34, which succeed each other in the longitudinaldirection X. Each fin 21 or equivalent has orifices 40 which areconfigured to allow the flow of the liquid refrigerant F1 through therespective fin 21 or equivalent.

In the example of FIGS. 1 to 5, each fin 21, 22, 23, 24, 31, 32, 33 or34 has an upper portion 21.1 and equivalent, and a lower portion 21.2and equivalent. When the distribution device is in operation (FIGS. 4and 5), the height of the upper portion 21.1 is greater than the heightof the lower portion 21.2.

Each lower portion 21.2 or equivalent, and the respective plate 11 orequivalent secured to the lower portion 21.2, define a distributionchannel 42 which is configured for conducting liquid refrigerant F1 inthe lateral direction Y.

In the example of FIGS. 1 to 5, the orifices 40 of each fin 21 orequivalent are formed by overflow openings 40 which are situated in eachrespective upper portion 21.1 or equivalent. All fins 21 and equivalenthave respective upper portions 21.1 and equivalent which have overflowopenings 40. For evident reasons of clarity, not all overflow openings40 are marked on FIGS. 1 to 5.

The overflow openings 40 of each fin 21 or equivalent are configuredsuch that the liquid refrigerant F1 flows via the overflow openings 40when the distribution channel 42 is full of liquid refrigerant F1.

All overflow openings 40 here have the shape of triangles pointingtowards each respective lower portion 21.2. The overflow openings 40 arehere distributed over a respective fin 21 or equivalent uniformly in thelateral direction Y.

An interval D40, measured in the lateral direction between twosuccessive overflow openings 40, is here constant and equal to 4 mm foroverflow openings 40 of each fin 21 or equivalent.

Also, a minimal distance H40 between i) an overflow opening 40, and ii)the plate 11 secured to the respective lower portion 21.2, is equal to 3mm. This minimal distance H40 is the same (constant) for all overflowopenings 40 of a respective fin 21 or equivalent.

In the example of FIGS. 1 to 5, the overflow openings 40 present in afin 21 are positioned offset in the lateral direction Y relative to theoverflow openings 40 present in the adjacent fin 22. The offset D40/2between the overflow openings 40 present in two adjacent fins 21 and 22here represents 50% of the length of interval D40.

Each overflow opening 40 here has an area equal to 4 mm². An openingratio having:

-   -   for the numerator, the total area of the overflow openings 40        situated in a fin 21 or equivalent with overflow openings 40,        and    -   for the denominator, the total area of a face 21.0 of this fin        21,

is here equal to 20%.

FIGS. 4 and 5 illustrate more particularly the function of thedistribution device 1. The liquid refrigerant F1 is shown shaded. AsFIGS. 4 and 5 show, the liquid refrigerant F1 overflows through eachoverflow opening 40 and fills each distribution channel 42 of the fins21, 22, 23, 24, 31, 32, 33 and 34.

As FIGS. 4 and 5 show, the volume of each distribution channel 42 (shownshaded on FIG. 4 or 5) is less than 10% of the total volume (shownchecked on FIG. 4) delimited by:

i) a respective fin 222 with overflow openings 240,

ii) the plate 11 secured to the lower portion of this fin 222, and

iii) the fin 221 situated immediately upstream of the fin 222.

FIG. 15 illustrates a distribution method according to the invention fordistributing the liquid refrigerant F1 in the heat exchanger 2. Thisdistribution method comprises in particular the steps:

1001) implementing the distribution device 1,

1002) conducting the liquid refrigerant F1 into the passages 20 and 30and globally in a longitudinal direction X,

1003) allowing the flow of the liquid refrigerant F1 through theorifices of the fins 21 and equivalent with openings 40,

1004) filling each distribution channel 42 such that the liquidrefrigerant F1 flows through the overflow openings 40; this step 1004)results in the operating state illustrated in FIGS. 4 and 5.

Each distribution channel 42 is globally horizontal when thedistribution device 1 is in operation. The cooperation of eachdistribution channel 42 with the overflow openings 40 allows the liquidrefrigerant F1 to be distributed as uniformly as possible in the lateraldirection Y.

As FIG. 3 shows, the heat exchanger 2 comprises a heat exchange unit,partially shown, with reference 4 in FIG. 3. Furthermore, the heatexchanger 2 comprises an inlet for calorigenic fluid F2 and an inlet 8for liquid refrigerant F1. The inlet 8 is here formed by perforations ina perforated bar 9.

The heat exchanger 2 also comprises the distribution device 1 which isconfigured to supply liquid refrigerant F1 to the heat exchange unit 4.In this case, the heat exchanger 2 includes a holding tank 3 in whichthe liquid refrigerant F1 is stored before flowing towards thedistribution device 1. In operation, the liquid refrigerant F1 passesthrough the distribution device 1.

Second and third embodiments of the invention share the feature that thetotal area of all overflow openings 140, 240, 241 for a given fin 121,122, 123, 124 increases from top to bottom. This may be achieved byincreasing the number and/or area of the openings.

FIGS. 6 and 7 illustrate a part of a distribution device 101 accordingto the second embodiment of the invention. Insofar as the distributiondevice 101 is similar to the distribution device 1, the description ofthe distribution device 1 given above in relation to FIGS. 1 to 5 may betransposed to the distribution device 101 with the exception of thesignificant differences explained below.

A component of the distribution device 101 which is identical orcorresponds in structure or function to a component of the distributiondevice 1 carries the same numerical reference increased by 100. Thus wehave plates 111, 112, fins 121, 122, 123, 124, overflow openings 140 anddistribution channels 142.

The distribution device 101 differs from the distribution device 1 inthat the overflow openings 140 have an elliptical shape. However, as inthe distribution device 101, each orifice of each fin 121, 122, 123, 124forms an overflow opening 140.

The fins 121, 123 have the same number of overflow openings, but theareas of the openings 140 of the lower fin 123 are smaller than those ofthe openings 140 of the higher fin 123. The openings 140 of the fin 121are fewer, but they have the same shape as those of the lower fin 122.This is also the case for the openings of fins 123 and 124. The totalarea of the openings increases in the direction from upstream todownstream (descending direction on FIG. 7), i.e. downward duringoperation of the exchanger.

FIGS. 8 and 9 illustrate a part of a distribution device 201 accordingto a third embodiment of the invention. Insofar as the distributiondevice 201 is similar to the distribution device 101, the description ofthe distribution device 101 given above in relation to FIGS. 6 and 7 maybe transposed to the distribution device 201 with the exception of thesignificant differences explained below.

A component of the distribution device 201 which is identical orcorresponds in structure or function to a component of the distributiondevice 101 carries the same numerical reference increased by 100. Thuswe have plates 211, 212, fins 221, 222, 223, 224, overflow openings 240and distribution channels 242.

The distribution device 201 differs from the distribution device 101since two fins 221 and 222 have orifices 241 which do not form overflowopenings 240. Only the fins 223 and 224 have overflow openings 240. Infact, the orifices 241 are few in number on fins 221 and 222 such thatthe orifices 241 are flooded when the distribution device 201 is inoperation.

The fins 221 and 222 are placed upstream of the fins 223 and 224 withoverflow openings 240. The orifices 241 are distributed in the lateraldirection. The number of overflow openings 240 per fin 223 or 224 isgreater than 5 times the number of orifices 241 per fin 221 or 222.

The number of orifices 241 per fin 221 or 222 increases in the directionfrom upstream to downstream (descending direction on FIG. 9), i.e.downward during operation of the exchanger. The interval D241.1 betweentwo successive orifices 241, measured in the lateral direction of thefin 221 with orifices 241 which is situated furthest upstream (at thetop on FIG. 9), is here equal to 51 mm. In fact, the spacing 11-12between plates 11 and 12 is approximately equal to 51 mm. The intervalD241.2 between two successive orifices 241, measured in the lateraldirection of the fin 222 with orifices 241 which is situated furthestdownstream, is here equal to 20 mm.

In contrast to the distribution device 1, when the distribution device201 is in operation, fins 221 and 222 with orifices 241 may fulfil afunction of controlling the flow rate of the liquid refrigerant enteringthe distribution device 201 while generating a high load loss, whereasfins 223 and 224 with overflow openings 240 rather fulfil a distributionfunction while generating only a low load loss.

FIG. 10 illustrates a part of a distribution device 301 according to afourth embodiment of the invention. Insofar as the distribution device301 is similar to the distribution device 1, the description of thedistribution device 1 given above in relation to FIGS. 1 to 5 may betransposed to the distribution device 301 with the exception of thesignificant differences explained below.

A component of the distribution device 301 which is identical orcorresponds in structure or function to a component of the distributiondevice 1 carries the same numerical reference increased by 300. Thus wehave plates 311, 312, a passage 320, and fins 321, 322, 323, 324.

The distribution device 301 differs from the distribution device 1 sincethe fins 321, 322, 323, 324 and the plates 311 and 312 are arranged in azone of the distribution device 301 in which the passage 320 isrelatively wide, because this zone has no conduits for calorigenic fluidF2. In fact, each conduit for calorigenic fluid F2 is blocked by astopper 350, and the outlet (not shown) of the conduits for calorigenicfluid F2 is located on a lateral face of the distribution device 301.

Therefore at the level of the fins 321, 322, 323, 324, the passages 320may be arranged over the entire height, measured in the direction Z, ofthe distribution device 301, whereas the passages 20 and 30 alternatewith respective conduits for calorigenic fluid F2. For example, thespacing 311-312 between the plates 311 and 312 is approximately equal to110 mm, whereas the spacing 11-12 between the plates 11 and 12 isapproximately equal to 51 mm.

Thus the fixing portion of each fin 321, 322, 323, 324 is relativelysmall, which reduces the stresses on the brazing fillets formed betweenthe plate and the fin.

Also, the fins 321, 322, 323, 324 may have orifices and overflowopenings configured as in the first embodiment (FIGS. 1 to 5: constantnumber of overflow openings) or as in the third embodiment (FIGS. 8 and9: progressive increase in the number of orifices).

FIG. 11 illustrates a part of a distribution device 401 according to afifth embodiment of the invention. The distribution device 401 combines:

-   -   fins 421 and 422 arranged in a zone in which the spacing between        plates 411 and 412 is large (e.g.: 110 mm),    -   with fins 423, 424 and equivalent arranged a zone in which the        passage 420 is constricted (e.g.: 55 mm) because of the        alternate presence of conduits for calorigenic fluid F2.

Each conduit for calorigenic fluid F2 is blocked by a stopper 450, andthe outlet (not shown) of the conduits for calorigenic fluid F2 issituated on a lateral face of the distribution device 401.

The fins 421, 422 arranged in the wide zone of passage 420 may haveorifices but not overflow openings, whereas the fins 423, 424 arrangedin the narrow zone of passage 420 may have overflow openings.

FIG. 11 illustrates a part of the distribution device 501 according to asixth embodiment of the invention. The distribution device 501 issimilar to the distribution device 1. The distribution device 501comprises plates 511, 512 and equivalent, an inlet 508 for liquidrefrigerant, fins 521 and equivalent, and a stopper 550 for blocking theconduits for calorigenic fluid F2.

The distribution device 501 differs from the distribution device 1 sincethe zone in which the holding tank 503 is arranged is wider than thezone in which the holding tank 3 is arranged, which allows an increasein the distance between the plates 511 and 512 and each orifice formingthe inlet 508 for liquid refrigerant. Thus the risk of partial or totalblockage of each of these orifices due to capillary action from brazingis reduced or avoided. Furthermore, this wider zone allows largerorifices to be defined for the flow of liquid refrigerant.

Naturally, the invention is not limited to the particular examplesdescribed and illustrated in the present application. Other variants orembodiments within the reach of the person skilled in the art may alsobe considered without leaving the scope of the invention as defined bythe attached claims.

Thus, as an alternative to the embodiments described above, the fins mayhave profiles other than flat and oblique. For example, FIG. 13illustrates a part of a distribution device 601 in which the fins areflat and composed of an oblique strip and a lateral strip which ishorizontal when the distribution device is in operation. Similarly, FIG.13 illustrates a part of a distribution device 601 in which the fins areflat and sinusoidal.

While the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, it is intendedto embrace all such alternatives, modifications, and variations as fallwithin the spirit and broad scope of the appended claims. The presentinvention may suitably comprise, consist or consist essentially of theelements disclosed and may be practiced in the absence of an element notdisclosed. Furthermore, if there is language referring to order, such asfirst and second, it should be understood in an exemplary sense and notin a limiting sense. For example, it can be recognized by those skilledin the art that certain steps can be combined into a single step.

The singular forms “a”, “an” and “the” include plural referents, unlessthe context clearly dictates otherwise.

“Comprising” in a claim is an open transitional term which means thesubsequently identified claim elements are a nonexclusive listing (i.e.,anything else may be additionally included and remain within the scopeof “comprising”). “Comprising” as used herein may be replaced by themore limited transitional terms “consisting essentially of” and“consisting of” unless otherwise indicated herein.

“Providing” in a claim is defined to mean furnishing, supplying, makingavailable, or preparing something. The step may be performed by anyactor in the absence of express language in the claim to the contrary.

Optional or optionally means that the subsequently described event orcircumstances may or may not occur. The description includes instanceswhere the event or circumstance occurs and instances where it does notoccur.

Ranges may be expressed herein as from about one particular value,and/or to about another particular value. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value and/or to the other particular value, along withall combinations within said range.

All references identified herein are each hereby incorporated byreference into this application in their entireties, as well as for thespecific information for which each is cited.

1-14. (canceled)
 15. A heat exchanger configured for transferring heatfrom at least one calorigenic fluid to at least one frigorigenic fluid,the heat exchanger comprising: plates arranged parallel to each other soas to define a first series of passages configured for conducting liquidrefrigerant globally in a longitudinal direction extending in thevertical direction during operation, each passage being defined betweentwo successive plates, and a second series of passages configured forconducting a calorigenic fluid globally in the longitudinal direction,each passage being defined between two successive plates, the passagesof the second series being interposed between two passages of the firstseries; at least one inlet for liquid refrigerant configured to pour theliquid refrigerant only into the passages of the first series; anddistribution means situated in the upper end of the exchanger inpassages of the first series only, comprising fins extending in one oreach passage of the first series globally in a lateral direction whichis orthogonal to the longitudinal direction and parallel to the plates,each passage of the first series housing several fins succeeding eachother in the longitudinal direction, wherein each fin comprises orificesconfigured to allow the flow of the liquid refrigerant; wherein at leastone fin having an upper portion and a lower portion, the height of theupper portion being greater than the height of the lower portion whenthe distribution device is in operation and the longitudinal directionextends in the vertical direction, wherein said at least one lowerportion and the plate secured to said at least one lower portiondefining at least one distribution channel configured for conductingliquid refrigerant in the lateral direction, wherein the orifices ofsaid at least one fin being formed by overflow openings situated in saidat least one upper portion, the overflow openings being configured suchthat the liquid refrigerant flows via the overflow openings when said atleast one distribution channel is full of liquid refrigerant.
 16. Theheat exchanger as claimed in claim 15, wherein the volume of arespective distribution channel is less than 15% of the total volumedelimited by: i) a fin with overflow openings, ii) the plate secured tothe lower portion of said fin with overflow openings, and iii) the finsituated immediately upstream of said fin with overflow openings. 17.The heat exchanger as claimed in claim 15, wherein the overflow openingsare distributed over a fin uniformly in the lateral direction.
 18. Theheat exchanger as claimed in claim 15, wherein an opening ratio having:as numerator, the total area of the overflow openings situated in a finwith overflow openings, and as denominator, the total area of a face ofsaid fin with overflow openings, is between 10% and 50%.
 19. The heatexchanger as claimed in claim 15, wherein each overflow opening has anarea between 1.5 mm² and 10.0 mm².
 20. The heat exchanger as claimed inclaim 15, wherein an interval measured in the lateral direction betweentwo successive overflow openings is between 1 mm and 6 mm.
 21. The heatexchanger as claimed in claim 15, wherein a minimal distance between i)an overflow opening, and ii) the plate secured to said at least onelower portion, lies between 1 mm and 4 mm.
 22. The heat exchanger asclaimed in claim 21, wherein the minimal distance is the same for themajority or totality of overflow openings of a respective fin.
 23. Theheat exchanger as claimed in claim 15, wherein several fins haverespective upper portions with overflow openings.
 24. The heat exchangeras claimed in claim 23, wherein the overflow openings present in a finare positioned offset in the lateral direction relative to the overflowopenings present in the adjacent fin.
 25. The heat exchanger as claimedin claim 24, wherein said offset between the overflow openings presentin two adjacent fins represents between 40% and 60% of the length ofsaid interval.
 26. The heat exchanger as claimed in claim 15, wherein atleast one fin has a flat shape and extends up to said two successiveplates and obliquely to each of said two successive plates so as toform, in cross-section in a plane perpendicular to the plates and to thelateral direction, an acute oblique angle.
 27. The heat exchanger asclaimed in claim 15, wherein the oblique angle is between 30° and 60°.28. The heat exchanger as claimed in claim 15, wherein each fin has,parallel to the longitudinal direction, a length between 4 mm and 10 mm,and wherein each fin has, parallel to the lateral direction, a widthbetween 4 mm and 10 mm, each fin being able for example to have equallength and width.
 29. The heat exchanger as claimed in claim 15,comprising at least one fin having orifices and placed upstream of thefin(s) with overflow openings, the orifices being distributed in thelateral direction, the number of overflow openings per fin being greaterthan 3 times the number of orifices per fin.
 30. The heat exchanger asclaimed in claim 15, wherein the total area of the openings or of theoverflow openings for a given fin increases in the longitudinaldirection by increasing the number and/or area of the openings.